In the chapter dealing with the canonical grouping known as "The Prophets", Walter Brueggemann asks where "new truth comes from".

We are immediately pressed to recognise that new revelation must come from unlegitimated sources because there is a closed circle between old revelation and its proponents. That circle will be broken and shattered only by a new voice which has no such vested interest. New truth from G-d is lilely to come as a cry and a protest of the weak, the powerless, the disinherited ones. In the Old Testament, the new truth comes from among and in behalf of the widows and orphans, the ones trampled by conventional "justice". In our own time, it is the economically disinherited, the ploticakly powerless, the ecclesiologically excluded who cry a new truth from G-d.

Powerful words - but how do we recognise new truth as a revelation from G-d, rightly addressing abuse and oppression, compared to special pleading from a minority group that simply refuse to accept what G-d has clearly said?